Bourbaki dangerous bend symbol: Difference between revisions
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which defines the abbreviation <code>\dbend</code> for it. |
which defines the abbreviation <code>\dbend</code> for it. |
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In [[LaTeX]] version 3, a passage can be marked with a dangerous bend or double dangerous bend symbol using one of the two environment commands:<ref>Frank Mittelbach, Michel Goossens, Johannes Braams, David Carlisle, Chris Rowley, Christine Detig, and Joachim Schrod (2004), ''The LaTeX Companion'', [http://www.latex-project.org/guides/tlc2-ch3.pdf Chapter 3: Basic Formatting Tools], Addison-Wesley.</ref> <pre>\begin{danger} ... \end{danger} |
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\begin{ddanger} ... \end{ddanger}</pre> |
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In HTML the unicode dangerous bend symbol ☡ can be produced by: <pre>&#x2621;</pre> |
In HTML the unicode dangerous bend symbol ☡ can be produced by: <pre>&#x2621;</pre> |
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Revision as of 03:03, 5 September 2011
Certains passages sont destinés à prémunir le lecteur contre des erreurs graves, où il risquerait de tomber; ces passages sont signalés en marge par le signe ☡ («tournant dangereux»)
Some passages are designed to forewarn the reader against serious errors, where he risks falling; these passages are signposted in the margin with the sign ☡ ("dangerous bend")
— Nicholas Bourbaki's description of the symbol in several textbooks[1]
The dangerous bend or caution symbol ☡ (unicode U+2621, "CAUTION SIGN") was created by the Nicolas Bourbaki group of mathematicians and appears in the margins of mathematics books written by the group. It resembles a road sign that indicates a "dangerous bend" in the road ahead, and is used to mark passages tricky on a first reading or with an especially difficult argument.[2]
Others have used variations of the symbol in their textbooks, and computer scientist Donald Knuth introduced a more realistic road-sign depiction in his Metafont and TeX systems, with a pair of adjacent signs indicating doubly dangerous passages.[3][4][5]
Typography
In the LaTeX typesetting system, Knuth's dangerous bend symbol can be produced by
\font\manual=manfnt
\def\dbend{\manual\char127}
which defines the abbreviation \dbend for it.
In HTML the unicode dangerous bend symbol ☡ can be produced by:
☡
References
- ^ See, for example, Théorie des ensembles, p. I-8.
- ^ Steven G. Krantz (2011), The Proof Is in the Pudding: The Changing Nature of Mathematical Proof, Springer, ISBN 0387489088, p. 92.
- ^ Donald Ervin Knuth (1984), The TeXbook, Addison-Wesley, ISBN 0201134489.
- ^ Donald Ervin Knuth (1986), The METAFONTbook, Addison-Wesley, ISBN 0201134454.
- ^ George J. Tourlakis (2003), Lectures in Logic and Set Theory, Volume 2: Set Theory, Cambridge University Press, ISBN 0521753740, p. xiv.